There have been known a variety of containers for sealingly containing gas or a liquid.
When a container is used as a material of, for example, a lifesaving buoy, a boat or the like, the container is designed such that all the air contained therein is sealed by a valve or a stopper disposed inside or outside of the container.
In such conventional arrangement, if a lifesaving buoy, a boat or the like is damaged at a portion thereof, all the air sealed therein flows out. This is very dangerous, lacking the safety. Such problem also applies to a buffer material, an air pillow or the like formed by filling the container with air. The outflow of all the fluid sealed in the container through one damaged portion thereof presents a great disadvantage.